Pertinent Pearls On Fifth Metatarsal Osteotomies

Which osteotomy offers the most advantages for treating a tailor’s bunion? Offering insights from their experience as well as a thorough review of the literature, these authors offer a closer look at options ranging from distal metatarsal osteotomies and the lateral exostectomy to transverse and oblique osteotomies.

The bunionette, or tailor’s bunion, is a deformity of the lateral or dorsolateral aspect of the fifth metatarsal. It is often a painful condition that shoe wear typically exacerbates. Retrospective studies have shown this condition is three to 10 times more common in women than men and arises predominantly in one’s 30s and 40s.1 Although authors have yet to agree to a single etiology, researchers have offered numerous theories in the literature.

Potential congenital etiologies identified in the literature have included: incomplete development of the transverse metatarsal ligament; the presence of a supernumerary bone lateral to the fourth metatarsal head; and the presence of an enlarged metatarsal head/condyles.2-5

Additionally, authors have cited aberrant biomechanical forces as a primary etiology. Hicks noted that excessive abduction of the fifth metatarsal would be irritating to the fifth metatarsal in shoes.6 Root identified many biomechanical abnormalities that could potentially lead to the formation of a tailor’s bunion. These abnormalities included abnormal subtalar joint pronation, uncompensated forefoot and rearfoot varus, and a plantarflexed position of the fifth ray.7

Structural and positional abnormalities including prominent lateral condyles of the fifth metatarsal head, and/or angular deformities of the fourth and fifth metatarsals also may contribute to this deformity. Fallat and Buckholtz identified several entities that could be associated with the presence of a tailor’s bunion. These entities include an increased intermetatarsal angle between the fourth and fifth metatarsal heads, an increased lateral deviation angle, lateral rotation of the plantar lateral condyle, a large dumbbell-shaped fifth metatarsal head, arthritic changes with bony exostosis at the fifth metatarsophalangeal joint, and any combination of the aforementioned conditions.8,9

The clinical presentation will typically reveal a painful and prominent metatarsal head with a subsequent corresponding hyperkeratotic skin lesion. This is often visible in the presence of erythema and may include an adventitious bursa.9 The fifth digit may exhibit an adductovarus position with or without corresponding skin lesions including both heloma molle formation and Lister’s corns.8-10

Conservative management should include shoe gear modifications such as wider toe box shoes, orthotics and padding of areas of prominence. When appropriate, one should debride lesions and attempt corticosteroid injections for treatment of an inflamed bursa.9,10 Clinicians may also use oral anti-inflammatory medications and analgesics adjunctively.1 Although conservative therapy may provide short-term relief, surgical intervention is often needed.1,9,10

A Guide To Preoperative Considerations And Incision Placement

Ensure that the patient is in a supine position. Bear in mind that many patients will externally rotate the lower extremities once they receive anesthesia. This makes appropriate visualization of the surgical target difficult.1,10 To avoid this, it is best to place a sandbag under the ipsilateral buttock. Tilting or “airplaning” the operating table toward the opposite extremity will also aid in visualization.10

Hemostasis will also help with keeping the surgical field clear for identifying vital structures. One can achieve this with the use of a pneumatic ankle tourniquet or administration of a local anesthetic agent with epinephrine (1:100,000).1,9,10

The surgeon would optimally place a linear or curvilinear incision roughly 3 cm in length, beginning from the midshaft of the fifth metatarsal and extending distally.9-11 Typically, a dorsolateral incision is preferred. This will ensure adequate exposure to all necessary structures.9-11 Take care around this area due to the tributaries of the lateral marginal vein. Layered dissection will allow for visualization of these structures and one should appropriately ligate and cauterize them as needed.

Additional structures to note in this area include the neurovascular bundle. If it is visible, one can safely retract this out of the surgical field. Identifying and safely retracting vital structures away from the surgical site will allow for the use of a longitudinal incision through the deep fascia and the periosteum. The senior author prefers to use a Freer elevator to assist with subperiosteal dissection, maintaining that it is generally easier to begin this dissection proximally as the periosteum adheres less to the bone at this level. It is important to resect enough periosteum to accommodate your osteotomy but do not be overly aggressive with this dissection as it can be detrimental to healing.

Weighing The Pros And Cons Of Lateral Exostectomies And Distal Metatarsal Osteotomies

Lateral exostectomy. The lateral exostectomy is a technically simple procedure that offers reproducible results. It continues to be in use today as both an individual and adjunct procedure. Things to note with this procedure include minimal soft tissue dissection and resection. When using the lateral exostectomy as a sole procedure, it is not necessary to carry dissection into the joint capsule. This will lead to less postoperative fibrosis. It is also vital to remove only one-fourth to one-third of the diameter of the bone.3,4,10 This will prevent destructive changes to the joint long term as well as postoperative dislocation. This procedure also has the advantage of allowing the patient to bear weight on the foot immediately postoperatively in a surgical shoe.9-11

Distal metatarsal osteotomies. Distal metatarsal osteotomies occur at the metaphyseal-diaphyseal junction of the fifth metatarsal.9-12 Surgeons have traditionally noted that these osteotomies are appropriate procedures for those deformities that are moderate in severity yet require more correction than a lateral exostectomy can yield.9,10 The senior author has found that distal osteotomies are incredibly versatile procedures and are capable of correcting a majority of the deformities podiatric surgeons encounter.

Distal metatarsal osteotomies are wonderfully reproducible and predictable procedures for several reasons, the first being that placement of these osteotomies is in a location that is predominately cancellous bone.9-11 Due to the increased vascularity that this affords, these osteotomies are at a reduced risk for non-union, malunion or delayed union. The senior author has also found that these procedures are technically less difficult than some of the more proximal osteotomies. This allows for decreased time under anesthesia, which in turn leads to a decreased morbidity for patients. With experience and the variety of procedures that are appropriate to execute at this location, the senior author can typically find a preferable procedure.

Key Insights On Transverse And Oblique Osteotomies

Transverse osteotomy. Some of the more traditionally utilized procedures include the transverse (Hohmann), oblique (Helal) and Chevron, to name a few. The transverse osteotomy, although technically easy, may be less favorable as it is not capable of providing as much correction as some of the other osteotomies.9,10,13,14 Only consider the transverse osteotomy when the deformity requires a minimal amount of displacement.9

Remember, when choosing this procedure, you can only shift the capital fragment a small amount. Therefore, adequate space medial to the head of the fifth metatarsal is necessary for the head to displace appropriately. Another thing to take into consideration is that because this osteotomy is slightly distal to the metaphyseal-diaphyseal junction, the healing potential will not be as optimal. Also, these osteotomies do not lend themselves well to internal fixation.9,10

Oblique osteotomy. Since its original description in 1975, surgeons have used the oblique osteotomy extensively for tailor’s bunion correction.9,12 Various authors have described a variety of modifications to this procedure and numerous studies validate its effectiveness.9,12

The senior author has found that the oblique osteotomy (Helal) is a procedure that lends itself to a wide range of angular deformities. One can manipulate the obliquity of the cut to account for the amount of desired correction. By increasing the obliquity of the osteotomy, not only does one get the amount of correction desired but one can also usually avoid a proximal procedure.

It should be noted that the amount of medial shift obtained is also proportional to the amount that the metatarsal will shorten. The senior author has not found this to be a problem long-term. The amount of shortening clinically is typically not significant and patients do not seem to be very concerned with it. However, if you are planning on combining the oblique osteotomy with an additional fifth digit arthroplasty, this becomes more relevant. As always, this is something to review with the patient on the informed surgical consent.

Surgeons can certainly combine the distal osteotomies with a lateral exostectomy but this is not always needed. In any case, always perform the exostectomy last so one can appropriately decide if it is in fact necessary.9,10,11,15

Fixation for oblique osteotomies can occur with a variety of screws and/or Kirschner wires. The senior author’s personal preference for the distal oblique osteotomy is typically a single screw (2.0 cortical) or a 0.062 mm K-wire. When utilizing the Kirschner wire, the senior author will drive it from proximal lateral to distal medial. Although this may seem technically unconventional (as it is generally not recommended to fixate from least stable to most stable), it is easier to perform and allows one to see that the K-wire is not entering the joint.

Regardless of the choice of fixation or even the specific osteotomy, the distal procedures typically lend themselves to immediate “heel” weightbearing.1,9,10,15 Again, this is important as the possibility of immediate weightbearing means patients are not intimidated by circumstances that may interfere too much with their day-to-day lives.

Navigating Proximal Osteotomies

Proximal osteotomies. These osteotomies will allow for the greatest degree of correction. However, they are technically difficult and one must select them only in appropriate scenarios. Historically, surgeons considered these procedures as less favorable options due to the delicate blood supply to the base of the fifth metatarsal as well as the instability of the osteotomies themselves.1,15 The deformities well suited for this type of procedure include those with a significantly increased fourth-fifth intermetatarsal angle and splay foot deformities.9,10 Gerbert’s indications included a non-arthritic joint in the presence of a deformity that involved the entire metatarsal.16

When faced with a deformity that is appropriate for treatment with a proximal osteotomy, the senior author prefers a reverse closing base wedge osteotomy. Several things to be cautious of include meticulous dissection to avoid the lateral dorsal cutaneous nerve and avoid violating the joint between the fourth and fifth metatarsal bases while making the cut itself.1,9,10,11 Proper fixation and stabilization is absolutely critical as these osteotomies are more prone for delayed/non-union. Some authors have recommended placing this osteotomy in the proximal portion of the diaphysis in order to decrease the risk of delayed or non-union.17

The postoperative course will need to involve cast immobilization, analogous to that of a closing base wedge osteotomy one would use to correct a severe hallux valgus deformity.9,10

What You Should Know About Ancillary Procedures

It is important to evaluate the fifth toe in the presence of a tailor’s bunion. Just as a deviated hallux applies a retrograde force onto the first metatarsal, thus increasing the intermetatarsal angle in a hallux valgus deformity, an adductovarus fifth toe will have the same effect on a fifth metatarsal. This obviates the need for correction.1,9 You must consider, however, that this can increase the amount of shortening of the fifth ray when it is combined with a distal or proximal osteotomy.

How To Remediate Complications

Complications of tailor’s bunion correction are similar to many other surgeries. These complications include a painful/unsightly scar, neuritis/nerve entrapment, infection and transfer lesion/metatarsalgia.9,10 We advocate fixation of these osteotomies as the literature has shown that fixation will allow for increased rates of healing and consolidation as well as decreased rates of non-union/delayed union.17 In addition, researchers have shown that fixation decreases the amount of dorsal displacement of the capital fragment, thus preventing transfer lesions and metatarsalgia.17

In Conclusion

It is important to evaluate these procedures appropriately and determine which procedure will work best in your hands for each type of deformity. Re-familiarize yourself with the anatomy of the fifth ray and plan accordingly to avoid transection of any vital structures. Be open and honest with your patients about your decision making process and what they can reasonably expect postoperatively.

Dr. Pontious is a Professor and Chair of the Department of Surgery at the Temple University School of Podiatric Medicine in Philadelphia.

Dr. Creech is a second-year resident at Temple University Hospital in Philadelphia.

For further reading, see the DPM Blog “What Is The Best Way To Treat A Tailor’s Bunion?” at http://tinyurl.com/bzgst85 or “A Guide To Hybrid Screw Fixation In Lesser Metatarsal Surgery” in the January 2008 issue of Podiatry Today. To access the archives, visit www.podiatrytoday.com.